Abbrev. Guilt Tripping. Short for Guilt Tripping: using guilt to sway someone to perform or provide favors.
Ex: "Are you GTin' me?" Meaning are you guilt tripping me, trying to make me feel guilty about something for your personal gain? Or "Damn, stop GTin' him, he ain't gonna fall for that..." or
"Damn, everybody be GTin' me all da time."